HOW TO DECREASE OVERAGING IN PB-CA-SN ALLOYS

It is known that lead-calcium-tin alloys are very well hardened by con tinuous precipitation since 20 degrees C. But an overaging involving a decrease of the mechanical properties appears afterwards. It is prove d in this study that with an adapted combination of the composition of the Pb-Ca-Sn alloys and a specific heat treatment it is possible to r each a hardness of 25 to 30 Vickers with a complete precipitation of ( Pb1-xSnx)(3)Ca and to suppress practically any overaging in as-cast or rolled specimens. (C) 1998 Elsevier Science S.A.